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IGMinimumSeparators misbehaves with directed graphs #48

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szhorvat opened this issue May 2, 2017 · 4 comments
Open

IGMinimumSeparators misbehaves with directed graphs #48

szhorvat opened this issue May 2, 2017 · 4 comments

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@szhorvat
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szhorvat commented May 2, 2017

According to the documentation, edge directions should be ignored.

In reality, empty results are returned for directed graphs.

In[385]:= IGMinimumSeparators@CycleGraph[4, DirectedEdges -> True]
Out[385]= {}

In[386]:= IGMinimumSeparators@CycleGraph[4, DirectedEdges -> False]
Out[386]= {{2, 4}, {1, 3}}

Upstream bug: igraph/igraph#992

@szhorvat szhorvat added this to the 0.4 milestone May 2, 2017
@Juddd
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Juddd commented Jul 5, 2017

I also don't think it works normally with undircted graph,see this

edges = {TX -> R1, R1 -> R3, R3 -> R5, R5 -> RX, TX -> R2, R2 -> R4, 
   R4 -> R6, R6 -> RX, R1 -> R2, R2 -> R3, R3 -> R4, R4 -> R5, 
   R5 -> R6, TX -> R7, TX -> R8, R7 -> R9, R9 -> R6, R9 -> RX, 
   R8 -> R6};
g = UndirectedGraph[edges, VertexLabels -> "Name"]
IGMinimumSeparators[g]

Mathematica graphics

@szhorvat
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szhorvat commented Jul 5, 2017

I think this result is correct. Can you explain more why you think it is not?

Deleting these vertex sets disconnects the graph. They are indeed the smallest possible sets that will disconnect it.

@Juddd
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Juddd commented Jul 5, 2017

I'm soory,I make a mistake.There is a isolated vertex(R8) when we drop the vertice R6 and TX..The result is right indeed.

@szhorvat szhorvat removed this from the 0.4 milestone Dec 25, 2017
@szhorvat
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Milestone removed as there is a workaround for this in Mma code. Will keep the bug open until the issue is fixed in the C code upstream.

@szhorvat szhorvat added this to the 0.4 milestone May 9, 2019
@szhorvat szhorvat removed this from the 0.4 milestone Mar 30, 2020
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